adat m20 startup error

hi-
can anybody tell me what the deal is here, with my m20? when I turn on the power switch, sometimes the machine will startup normally, no problems; sometimes it will startup into an EPROM test mode, from which I can't get out of, save I power off- but if I initiate the EPROM test, it WILL do that, and the message I get is that it passed, but I still can't power up into normal mode from there, by pressing the eject button, and must power off the machine and try again.
if I press record buttons #1 + 7 simultaneously, then turn on the power, sometimes it will go into the extended test mode, which includes numerous tests you can scroll through, which will all work correctly, if I initiate them. from there, when I'm done with all my tests, if I press the eject button, it will then reboot from extended test mode into a normal operating mode, no problem, every time- but sometimes, If i press record buttons 1 + 7 simultaneously, then turn on the power, it will NOT go into the extended test mode, but will go into the EPROM test mode- from which I can NEVER get into normal operating mode---
right now, the problem has progressed to, no matter what I do, or which buttons I press, I cannot boot up into normal operating mode, and I can't get into the extended test mode either, from which I COULD reboot into normal operating mode. the ONLY mode I can get into anymore is the EPROM test mode- from which I CAN'T boot into normal operating mode!
is anybody familiar with this problem, and can tell me what the solution for it might be?